1. Technical Field
The present invention relates to an entrance barrier comprising a barrier element movable between an open and a closed position, driving means, by which the barrier element can be driven from one position to the other respectively, a control unit, by which the driving means are controllable, and a sensor unit connected to the control unit. The invention also relates to a barrier element for the entrance barrier and to a method for operating the entrance barrier.
2. Discussion
Entrance barriers of the above-described type are used in the prior art for a variety of applications, for instance for controlling the entrance or access to areas which are protected and/or subject to a charge. Entrance barriers are frequently used for instance in public transport, airports, especially in security checks, and also in public buildings such as swimming pools or sports facilities. They serve among others to grant access only to authorized persons or to grant only single access of persons.
In a security check for instance, an entrance barrier is provided in the form of two mutually opposite door wings which are driven for swiveling and which are automatically swung to an open position when an authorized person desires access and wants to pass the entrance barrier. To this end, the person inserts an access authorization card in a checking station capable of verifying authorization, and if the authorization is valid, the control unit connected to the checking station controls the driving means to move the door wings of the swing doors to the open position, whereupon the individual is allowed to pass the open entrance barrier. After passing the entrance barrier, the door wings are automatically closed again. Passage of the entrance barrier is detected by the sensor unit, and a corresponding signal is transmitted to the control unit. After passage of the entrance barrier, the barrier element is moved to the closed position. A light barrier is used as a sensor unit, which substantially enables a selective detection of a current position of a person. But this detection is insufficient, because the substantially linear detection area of the light barrier is very small. It is not possible to detect a person outside of the detection area. An additional drawback is that the light barrier delivers false detection values caused by the influence of ambient light. This may cause faulty control by the control unit.
To avoid that a person is hurt by the movement of the door wings, the energy transmittable from the driving means to the door wings is limited. If a person is still present in the movement range of a door wing during the opening or closing movement of this door wing, because the person has changed his/her direction of movement or stopped moving, the door wing will hit the person and stop its movement due to the limited energy, so that the person is hurt as little as possible. Accordingly, the entrance barrier provides passive safety. On the other hand, the mere contact between the person and the door wing may cause painful collisions, if not even injuries, especially if the person carries pieces of luggage. Moreover, this concept of passive safety puts limitations to the design of the door wings, particularly with regard to the weight, size and speed of movements. It is precisely this area where a light barrier cannot be installed, because the light barrier would interfere with the intended function of the door wing.